1. Field of the Invention
This invention relates generally to apparatus for screeding concrete and the like, and more particularly, but not by way of limitation, to apparatus for providing a self-propelled concrete screeding machine.
2. Description of the Prior Art (Prior Art Statement)
The following statement is intended to be a Prior Art Statement in compliance with the guidance and requirements of 37 CFR SS1.56, 1.97 and 1.98 and with S609 of the Manual of Patent Examining Procedure
The most relevant prior art reference known to Applicant is U.S. Pat. No. 3,412,658 issued to Griffin. Griffin is relevant in that it shows a self-propelling concrete screeding machine which uses a cable and winch assembly to provide for propulsion of the screed machine. It will be noted, however, that the Griffin device provides only a single winch 82 about which is wound a single cable 84, said single cable 84 being attached to the winch at a point intermediate the ends of the cable. Furthermore, it will be noted that the Griffin device does not include any level wind mechanism so as to provide for an even take-up of each end of the single cable 84. Two problems are inherent in such a self-propelling mechanism as is seen in Griffin. The lack of a level wind mechanism allows the cable to wrap upon the winch in a random manner thereby providing for an uneven take-up of each end of the cable. This causes one end of the Griffin apparatus to be pulled at a faster rate than the other end thereby propelling the Griffin apparatus in an irregular fashion.
Furthermore, the addition to Griffin of a satisfactory level wind mechanism would be frustrated by the fact that the Griffin device comprises only a single cable attached at an intermediate point to the winch. As will be seen in the later description of the present invention, in order to provide a satisfactory level wind mechanism it is necessary that a pair of level wind mechanisms be provided, each mechanism operating on a separate cable. This allows the two separate cables of the present invention to be wound upon separate spools with flanges intermediate the spools preventing interference of one cable with the other. Such a construction is not possible with the Griffin apparatus. The Griffin device also shows the use of an eccentric counter weight driven by the prime mover of the screeding device thereby imparting a vibrational motion to the screed machine.
U.S. Pat. Nos. 3,256,788 to Schweihofer, et al. and 2,306,671 to Tamblyn are of interest in that they also show a use of eccentrically mounted counter weights to impart a vibrational motion to a screeding machine.
U.S. Pat. Nos. 3,377,933 to Dale and 1,390,479 to Baker are of interest in that they show the use of winch and cable apparatus for providing propulsion means for paving machines. It will be apparent from an inspection of those two references that the propulsion means there provided are of considerably different design than that of the present invention.
Other references of somewhat peripheral interest showing various designs of concrete screeding machines are U.S. Pat. Nos. 3,435,740 to McGall; 3,368,466 to Rowe; and 2,813,467 to Vigneri.
Thus, it is seen that none of the prior art references disclose a self-propelled screeding machine having a winch and cable propulsion means provided with level wind mechanisms so as to cause the cables to be evenly wound upon the winch, thereby providing for an even take-up of each cable so that the screeding machine will be propelled in a regular fashion and will not be twisted to one side or the other. Furthermore, numerous refinements of the screeding machine of the present invention, such as the elongated guide shoe, and the improved demountable portable framework are not disclosed by any of the above references.